Used to be the odds of a woman giving birth to sextuplets was nigh near impossable too, but it still happened, even without the use of fertially drugs as a "drop mod." I'd say once every 3-4 generations of the entire population of the earth is fairly high odds.
To praphrase Sir Arthur Conan Doyle, "Once we have eliminated the impossible, whatever remains, no matter how improbable, must be the truth."
The odds that you exist are roughly 1 in 6,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, see math
here. You do exist, don't you? Good for you! you beat the odds!